A message sent on myspace, an email, text message, aim, ect. that has sexual content. Usually sent from a male who has sexual feelings for a female.

ryan12: Hey wats up?
clair85:nmu?
ryan12: nmj jacking off to you myspace picture.
clair85: wtf CREEP!!!
ryan12: I lov the one where your in a bathing suit and you can kinda see your nipple. DAMNNN!!!
( clair12 has blocked you from her buddy list.)

later that day...
Clair: OMG Ryan sent me the grosest sex message today!!
Julie: OMG! what a perv!